24-105 decentered lens.

Canon service has a hard time fixing decentered elements... Which I learned first hand with my first 24-70 II... In which the right side was soft compared to everywhere else. I sent to Canon NJ and it came back in the same condition with a receipt that basically said they were unable to correct the issue (don't remember exact wording). I even emailed Roger from Lens Rentals about my issue and he confirmed that they do have hard times correcting decentering without plenty of work to fix it. It can be done, but it generally has to be sent to them a few times before they do the labor intensive work. He suggested I just return and swap it out for another.